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And now with it all set up,

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once it restarted on my device, I can test it there.

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Now I will actually here send it to the same device

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as I'm running on,

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but this could be sent to any other device as well.

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I just don't have any second device around right now.

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But if I press trigger notification,

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you see sent via the app.

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Which clearly is that brand new message we prepared.

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So that is this push notification

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sent through Expo's push servers.

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And whilst I sent it to myself here, which of course

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might not be what you want to do in most scenarios.

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You still see the idea behind it.

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This could have been sent to any other application

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of which we had the push token.

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Now, speaking of that push token, though,

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how should you manage that?

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Because at the moment you could argue

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that the only push token we can know in this application

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is the one off this device on which this app is installed.

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So ho could we know the push token of some other device?

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How could that work?

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So we learned that we can leverage Expo push servers

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to deliver push notifications.

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But we need a push token for that.

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That's no problem because we can get that token

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as we do it here with get get.ExpoPushTokenAsync.

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The problem with that, however, is that,

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of course we can get a token with that

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and we can store this in state thereafter,

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but then we only have to token off this device

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on which this app installations running.

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So when we later want to send a push notification,

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the only token we know is our own token.

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Now for this example, this was just what we needed,

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but in reality, we of course want to send

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a push notification to other devices.

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So to the same app installed on other devices

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of other users, how would we get their tokens?

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Well, just as we get their emails

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or whatever else we need in an application.

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You can of course write code where once you got that token,

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you don't, or maybe not just manage it in your local state,

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but instead you send an HTTP request to your own API

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where you then have some logic to receive that token

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and store it in a database.

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This token of course can, and in reality will,

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be shared and stored in a database.

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So that any user of your app

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submits not just his or her email address and password,

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but also his or her push token.

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And with that data stored in a database on your server,

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you can, of course, always retrieve that token

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and use it in your app when you need it.

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So you can share that token,

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just like you share other user data as needed.

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After all, if a user creates a product

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in a shop application,

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we also store that product in a database

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to show it to other users as well.

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With a token, it's no different.

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We won't show it to other users,

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but we can still fetch it on the devices of our users

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and there use it in the code

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to send push notifications as shown here.

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In addition, it is worth pointing out that

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when it comes to sending notifications,

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there is a separate article on the Expo docs,

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and you can find it if you search for

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Expo push notifications and look for this

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Sending Notifications article.

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There, you will learn about different ways

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of sending notifications.

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One way is this way, that you use

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Expos push server like this.

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This is something you can do

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and there is nothing wrong with it.

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But if you don't really need to trigger

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the push notification from inside the app,

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but instead you want to trigger it from

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inside your own server.

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So now I'm talking about your server,

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which you as developer own.

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For example, the server where

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you also store products users create,

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and you wanna trigger a push notification

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from on that server, you can do that as well.

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The Expo team gives you many SDKs for Node, for Python,

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for PHP, which make it very easy to trigger

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push notifications on your own server.

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Under the hood, those SDKs

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will basically do what we do here.

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They will send the request to the Expo push server.

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Because that Expo push server,

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needs to be involved at all times.

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So those SDKs will still do that.

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But they can take away the need

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to run this logic inside of the app,

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and instead you could run it on your own server,

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if that would be something you needed.

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So you can really send push notifications in different ways.

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You can use the SDK like this,

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you can also just send a request

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to this Expo push API, as we did it here,

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and that in turn can be done

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from inside your app or even from outside of it.

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You could use any tool you want

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to send a post request with this data, to this URL.

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That doesn't have to happen inside of an Expo app.

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This is a regular HTTP request.

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So whenever you send a request configured like this,

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a push notification to that token, which you of course need,

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will be delivered.

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So that's how you can send push notifications.

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And that's how easy it is to get started

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with push notifications when you're using Expo.